This invention relates to automatic welding machines and in particular to an apparatus for seal welding tubes to the internal surface of a header.
Water tube boilers are formed of headers in the order of 16 inch outside diameter with tubes in the order of 2 inch outside diameter attached thereto. These tubes are attached on many occasions by using rolled joints. In this process tube drillings are supplied to accept the tubes and 4 inch handholes are supplied on the opposite side of the header at 15 inch intervals. The tube is placed through the hole extending slightly inside the header, and tube rolling equipment passed in through the handhole is used to roll and expand the tube into the joint. This forms the strength joint and also generally a leak-tight joint.
It is sometimes desirable to seal weld these tubes to the internal surface of the header when leaks develop or when the possibility of leaks is to be minimized. Because of the limited visibility and difficult access it is impractical to make effective seal welds on these tubes. The restricted size of the access openings and the limited space within the header precludes the use of conventional automatic welding equipment.
The apparatus of my invention is compactly arranged and organized to permit its introduction through the small handhole openings and its use within the restricted environment inside a header. The tube end may, therefore, be effectively and automatically seal welded to the inside surface of the header.